1. Field of the Invention
The present invention relates generally to the field of dentistry and, in particular, to dental appliances.
2. Description of Related Art
Dental appliances such as “invisible” retainers are now in regular use. Such dental appliances are made from a single material which is hard in order to retain its shape and exert sufficient pressure on a user's teeth.
U.S. Pat. No. 4,983,334 to Loren S. Adell shows a multilayer appliance forming a memory material.